Surface plasmon resonance (SPR) depends on the size and shape of
the nanoparticles. AuNPs possess unique SPR activity. To synthesize different
sizes of AuNPs different process parameters such as concentration
and volume of S. acuminata extract and HAuCl4 were tested in
this study. In the beginning different concentrations of S. acuminata extract
(10 mg/100 mL to 100 mg/100 mL of freshly dried fruit powder)
were used against constant concentration of HAuCl4 solution (5 mM)
and then the progress of the reaction was monitored by UV–
visible spectroscopic analysis. From the results it was found that
30 mg/100 mL concentration was sufficient to reduce the Au ions to
its nanoform (Au3+ to Au0
) completely. Finally volume ratio of both
precursor and extract at optimized concentrations was tested and it
was found that at 1:5 ratios (5 mM HAuCl4:30 mg/100 mL extract)
was required to synthesize AuNPs